MB had seat belt pretensioner on their experimental vehicle in 1971.

In 1981, [driver airbag + seat belt pretensioner] was available on S class. It was world's first.

In 1984, all MB's had front seat belt pretensioners.

According to http://www.mb-portal.net/html/story/story1.htm.


Currently, MB has Pre-Safe system on S class.
The pre-tensioning comes when the sensor detects that the driver does emergency braking or that the ESP is activated. This happens before collision. So the name pre-safe.
This is the world's first of this kind of system in production car.